title: HmuY haemophore and gingipain proteases constitute a unique syntrophic system of haem acquisition by Porphyromonas gingivalis.
abstract: Haem (iron protoporphyrin IX) is both an essential growth factor and virulence regulator for the periodontal pathogen Porphyromonas gingivalis, which acquires it mainly from haemoglobin via the sequential actions of the R- and K-specific gingipain proteases. The haem-binding lipoprotein haemophore HmuY and its cognate receptor HmuR of P. gingivalis, are responsible for capture and internalisation of haem. This study examined the role of the HmuY in acquisition of haem from haemoglobin and the cooperation between HmuY and gingipain proteases in this process. Using UV-visible spectroscopy and polyacrylamide gel electrophoresis, HmuY was demonstrated to wrest haem from immobilised methaemoglobin and deoxyhaemoglobin. Haem extraction from oxyhaemoglobin was facilitated after oxidation to methaemoglobin by pre-treatment with the P. gingivalis R-gingipain A (HRgpA). HmuY was also capable of scavenging haem from oxyhaemoglobin pre-treated with the K-gingipain (Kgp). This is the first demonstration of a haemophore working in conjunction with proteases to acquire haem from haemoglobin. In addition, HmuY was able to extract haem from methaemalbumin, and could bind haem, either free in solution or from methaemoglobin, even in the presence of serum albumin.
authors.affiliation: Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, [corrected] University of Liverpool, Liverpool, United Kingdom. josmall@liv.ac.uk
authors.forename: John W
authors.initials: JW
authors.lastname: Smalley
authors.forename: Dominic P
authors.initials: DP
authors.lastname: Byrne
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Birss
authors.forename: Halina
authors.initials: H
authors.lastname: Wojtowicz
authors.forename: Aneta
authors.initials: A
authors.lastname: Sroka
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
authors.forename: Teresa
authors.initials: T
authors.lastname: Olczak
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000378:metabolism / Q000502:physiology*; D004586:Electrophoresis; D055724:Electrophysiological Phenomena; D000080867:Gingipain Cysteine Endopeptidases; D006418:Heme / Q000737:chemistry / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D010108:Oxyhemoglobins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D016966:Porphyromonas gingivalis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011524:Protoporphyrins / Q000378:metabolism; D012709:Serum Albumin / Q000494:pharmacology
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D006454:Hemoglobins; D046912:Multiprotein Complexes; D010108:Oxyhemoglobins; D011524:Protoporphyrins; D012709:Serum Albumin; C448299:iron protoporphyrin IX; D006418:Heme; C100003:deoxyhemoglobin; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases